Heat interchanger



W; F. GIAUQUE HEAT INTERCHANGER May 16, 1950 Filed Sept. 25, 1945 FIB-15 Sheets-Sheet 1 MAL/AM 4 6/44/ 114 Arram/Ev May 16, 1950 w. F. .GIAUQUEHEAT INTERCHANGER 5 Sheets-Sheet 2 Filed Sept. 25, 1945 m/zwroz M1 1 MM56/4 4412 j W Arron 5y Q \E a May 16, 1950 w. F. GIAUQUE HEATINTERCHANGER 5 Sheets-Sheet 3 Filed Sept. 25, 1945 A TTO/C/VE Y PatentedMay is, 1950" HEAT m'rsncmwcna William F. Giauque, Berkeley, Calif.,assignor, by mesne assignments, to Research Corporation, New York, N.Y., a corporation of New York Application September 25, 1945, Serial No.618,439

This invention relates to heat interchangers, and is concerned moreparticularly with'heat interchangers constructed to obtain efficientheat transfer without excessive pressure drop.

It is a general object of the invention to pro vide an improved heatinterchanger adapted for use with fluids that will provide a high heat.

transfer by providing uniform flow conditions for both of the fluidspassing through the heat interchanger.

Another object of the invention is to provide an improved heatinterchanger in which a large area of heat interchange surface isprovided within a relatively small total volume of the interchanger.

Another object of the invention is to provide a heat interchanger ofhigh efficiency which is easy to manufacture by commercial manufacturingprocesses.

Other objects and advantages of the invention will be apparent from thefollowing description of the preferred embodiment thereof as illustratedin the accompanying drawings, in which:

Figure 1 is an elevational view of a heat interchanger embodying theinvention.

4 Claims. (Cl. 257-229) the length 'of paths provided in the varioustubes be substantially equal in length. Correspondmgly, for the fluidcontacting the outer surfaces of the tubes, it is important that flow offluid through the spaces between the tubes be maintamed substantiallyuniform by providing a substantially uniform dimension between thetubing at all points throughout the interchanger with excellentopportunity for cross mixing of fluids between the inter-tubing spaces.

The above objects are attained in the instant invention by the use ofconduits or tubes wound in helical layers, the interchanger unit beingcomposed of several such helical layers having a tubing arrangement toprovide a constant length of the several pieces of tubing used and toprovide a desired predetermined spacing radially with respect to thelayers of tubing and axially with Figure 2 is a horizontal sectionalview of the a heat interchanger-immediately below the upper manifoldthereof, and taken as indicated by the line 2-2 in Figure l.

Figure 3 is a horizontal sectional view of the mid portion of the heatinterchanger showing the arrangement of the crossover of the tubes, theview being taken as indicated by the line 3-3 in Figure l.

Figure 4 is a detailed elevational view of the spacing strip of thecoils of the heat interchanger.

Figure 5 is a sectional view of the spacer strip taken as indicated bythe line 5-5 in Figure 4.

Figure 6 is an enlarged fragmentary view illustrating a crossoverarrangement of the inner group of tubes.

Figure 7 is an enlarged fragmentary view illustrating a crossoverarrangement of the outer group of tubes. I

Figure 8 is a fragmentary enlarged view, partly in section, of an end ofa heat interchanger unit.

Figure 9 illustrates a typical heat interchange system employing heatinterchangers of the character disclosed herein.

In the construction of heat interchangers one important factor is thearrangement and relative disposition of the heat exchange surfaces ofmaximum area to provide for a uniform flow of the fluids through theinterchanger. Thus, it is important that the tubing employed to conductthe fluid in one direction be of uniform size and that respect toadjacent turns of a layer of tubing. In order to obtain the same lengthsof tubing in the various layers, in certain larger sizes of interchangerunits, the layers may be made of an increased number of tubes wound perlayer from the inside layer outward. With smaller interchanger units,the tubing which forms one layer, for example the outer layer of a groupof tubing, through one-half of the interchanger, is crossed over midwayof the length of the interchanger to form another layer, for example aninner layer of tubing. As a specific example, an interchanger having agroup of tubing wound in three layers of properly related averagediameters will be providedwith the same length of path of fluid flow inall the passes of the group by effecting a crossover between the innerand outer layers at the mid point of the interchanger. The same resultscan be obtained with any desired number of layers of tubing in a groupbut it is preferred to retain the number of layers small to cause lessunbalance in the flow outside the tubes.

In interchangers operating at sufliciently high pressures so that asmall pressure drop is not serious, it is preferred to use a crossoverarrangement of the passes to enable the use of a reduced number of tubesin parallel, and a consequent increase in heat transfer on the insidetube surface.

While in general and in the usual average or small size interchanger itis desirable to maintain a uniform spacing between the respective layersof tubing, with a large interchanger the greater curvature of the innerlayers will somewhat affect the flow outside of the tubes so that thespacing can be altered if desired to compensate for this effect and toobtain a substantially uniform flow ofthe fluid outside the tubes.

The invention has been illustrated in connec- 2,aoa,247

ing and with alternate layers wound oppositely to facilitate uniformityof heat transfer and cross mixing and to provide greater strength andrigidity. This type of interchanger also provides for a minimum numberof tubes in parallel within a la er.

iteferring to Figures' 1, 2, 3 and 8, the heat interchanger includes acentral post or support in the form of a pipe I around which two groupsof heat interchange tubes II and I2 are provided within a casing 9,each-group consisting of three layers of tubing. As the upper and lowerhalves of each group of tubing are similar, the detailed description ofthe construction of each group will be made with reference to the upperhalf thereof. As previously stated, each layer of tubing consists of ahelical coil of tubing of uniform spacing. The inner group of tubing IIincludes an inner layer II a, an intermediate layer H11 and an outerlayer Ilc, which are wound in the resent instance with two tubes inparallel. The inner layer Ila is disposed about the pipe I0 and isspaced therefrom by an appropriate number of circumferentially spacedlongitudinal spacer strips l3 which may be secured to the pipe In bysoldering so that the inner layer Ila of tubing is spaced from the pipeIII by the thickness of the spacer strips I3. The inner tubing layer Ilais also engaged by a plurality of spacer strips I4 (Figures 1, 2, 4 and5) which serves to space the inter mediate layer I lb from the innerlayer I la by the same amount as its spacing from the pipe I0. Eachspacer strip I4 has a series of struck-out ears I4a which are spacedapart a distance equal to the outer diameter of the tubing and projectinwardly between the adjacent turns of the inner tubing layer I la. sothat the turns are spaced apart an equal amount by the ears I4a of thespacer strips. The ends Nb of the strips I4 asshown in Figure 8 are bentover to engage the end turns of the coil and the pipe I0 and arevsecured thereto by soldered joints. If desired, the strips l4 and thetubing Ila may be secured together in assembled relation by soldering atan appropriate number of points. The middle layer Ill) and the outerlayer I lc are similarly mounted and secured by spacer strips I4 havingthe ears Ma interposed between the turns thereof.

As previously explained, the upper and lower halves of the interchangerare similar and at the midpoint of the interchanger a crossover iseffected between the inner and outer layers of the group while theintermediate layer remains in the same relative position. Referring toFigures 1, 3 and 6, it is seen that at the mid point of the interchangerthe inner layer I la of the upper half is connected by a soldered sleevejoint I5 tothe tubing of the outer layer lie of the lower half, whilethe tubing in the outer layer Ilc of the upper half is similarlyconnected by a sleeve It to the tubing of the inner layer Ila of thelower half. The middle layer Nb of both the upper and lower halves areof the same diameter. In this way each of thelayers Ila, IIb and Ho ofthe inner group are of the same length.

The outer group of layers I2 comprising an inner tubing layer I2a, amiddle tubing layer I2b and an outer tubing layer I20 are similarlyconstructed and arranged as the tubing of the inner group, except thatthis group is wound with three tubes in a set to provide a greater helixpitch or lead. The other length of the tubing can be made equal to thatof the inner group of tubes wound with two tubes at a time and acorrespond- 4 ing lesser lead. The outer tube group I2 is similarlyprovided with spacers I4 having spacing ears I4a.

At the lower end oi the heat interchanger the six pieces of tubing ofthe inner group II and the nine pieces of tubing of the outer group I2are connected to an annular manifold I1 which is The pipe may be closedby means of a plug 2|.

made of suitable heat insulating material.

Referring to Figure 9, a heat interchange system is shown employing apair of heat interchanger units I0 and Illa connected in series anddisposed within an insulating casing 22, this arrangement being of thetype employed, for example, in the manufacture of liquid oxygen.Associated with the heat interchanger group comprising theheat-interchanger units I0 and Illa is a forecooling refrigerant unit 23and a fractionating column 24 both of conventional construction andillustrated herewith to show a complete system. There is also provided asource 26 of high pressure air which is connected to the lower heatinterchange unit I0 through a conduit 21 to deliver high pressure air tothe lower end thereof. The air passes upwardly through the heatinterchanger unit I0 and is withdrawn from the upper end of this heatinterchanger unit through a conduit 28 connected to the refrigeratingunit 23 where a further cooling of the air is effected. The cooled airis brought back to the lower end of the upper heat interchanger Illathrough a conduit 29. The discharge from the upper end of the unit Illais provided through a conduit 3| which leads to the upper end of thefractionating column 24, the eiiluent from the top of the fractionatingcolumn 24 being returned through the pipe 32 to pass downwardly throughthe heat interchanger units Illa and II) to cool the air within thetubes and to be discharged at the bottom through a discharge elbow 33.

L Operation The operation of the heat interchanger will be described inconnection with the system shown in Figure 9. From the above descriptionit will be seen that high pressure air supplied through the inlet pipe21 will travel upwardly through the tubing of the lower heatinterchanger unit Ill, being cooled by the downwardly traveling eiliuentfrom the fractionating column 24 which travels through the spacesbetween the layers of tubing. The partially cooled air is carried fromthe manifold I9 at the upper end of the lower heat interchanger unit I0through the discharge pipe 28 to the forecooling unit 23 where it issubjected to refrigeration in the desired degree in accordance with thefiuidsbeing employed. The cooled air from the forecooling unit 23 isreturned through the pipe 29 which conducts it to the manifold Ila atthe lower end of the upper heat interchange unit Illa where, as ittravels upwardly, it is further subjected to cooling by the eflluentpassing downwardly through this heat interchanger. Preferably, thelength of the heat interchanger is so selected with respect to the usefor which it is intended so that the air will be cooled to theappropriate temperature for feed- -ing through the discharge pipe 3| tothe fractionating column 24 from which liquid oxygen can be obtained inthe usual manner.

atoms? While the description of the unit and its mode of operation havebeen made in connection with the production of liquid oxygen, it will beapparent that the heat interchangers, such as units It and ma, can beused singularly or in combination for any desired character ofheattransfer at high or low temperatures with the heat transfer taking placebetween, on the one hand, a fluid traveling through the helical coils oftubing and, on the other hand, a fluid traveling between the helicalcoils of tubing.

While I have shown and described a particular form of the invention, itwill be apparent that the invention can be modified or employed in otherforms without departing from the scope of the invention as defined inthe claims appended thereto.

I claim:

1. In a, heat exchanger, inlet and outlet manifolds spaced along alongitudinal axis, and a plurality of heat exchange tubes ofsubstantially equal lengthand diameter having their ends connected tothe manifolds, one group of said tubes being wound to form at least twohelixes disposed end to end and on different diameters and with acrossover connection between the helixes, the two sets of helixes thusformed by such tubes being nested and concentric with the helixes ofadjacent tubes, another group of said tubes being each wound to form atleast two helixes likewise disposed end to end and on difierentdiameters and with a crossover connection with the helixes, saidlast-named helixes being likewise nested concentric to each other andwith respect to the helixes of the first-named tubes, each of thehelixes formed by the tubes of the second group being formed by a numberof tubes greater than the number of tubes forming the helixes of thefirst group of tubes whereby the lead of helixes formed by the greaternumber of tubes is greater than that of the helixes formed by the lessernumber of tubes to obtain tubes of the same length in both groups. p

2. In a heat exchanger, inlet and outlet manifolds spaced along alongitudinal axis, and a plurality of heat exchange tubes ofsubstantially equal length and diameter having their ends connected tothe manifolds, one group of said tubes being wound to form at least twohelixes disposed end to end and on different diameters and with acrossover connection between the helixes, the two sets of helixes thus"formed by such tubes being nested and concentric with the helixes ofadjacent tubes, another group of said tubes being each wound to form atleast two helixes likewise disposed end to end and on differentdiameters and with a crossover connection with the helixes, saidlast-named helixes being likewise nested concentric to each other andwith respect to the helixes of the first-named tubes, longitudinalspacer strips between and contacting the tubes of said nested helixesand having laterally projecting ears extending between and contactingadjacent turns of each helix, each of the helixes formed by the tubes ofthe second group being formed by a number of tubes greater than thenumber of tubes forming the helixes of the first group 01 tubes wherebythe lead of helixes formed by the greater number of tubes is greaterthan that of the helixes formed by the lesser number of tubes to obtaintubes of the same length in both groups.

3. In a heat interchanger, a plurality of groups of conduits, each ofsaid conduits having substantially the same length and diameter, eachgroup comprising a plurality of sets of helically disposed similarconduits having a common helix axis and arranged in predeterminedradially spaced relation, the conduits of each set forming a layer ofthe same helical radius and lead, at least two sets of conduits formingrespective layers of a group at one end of the interchanger crossingover intermediate the ends of the interchanger to replace each other inthe respective layers to provide conduits of substantially the samelength in said sets, and the respective numbers of conduits in eachgroup being related to each other and to the respective diameters of thegroups of conduits to provide conduits of substantially the same lengthin said groups.

4. In a heat interchanger, a plurality of groups of conduits, each ofsaid conduits having substantially the same length and diameter, eachgroup comprising a plurality of sets of helically disposed similarconduits having a common helix axis and arranged in predeterminedradially spaced relation, the conduits of each set forming a layer ofthe same helical radius and lead, the sets of conduits forming theextreme inner and outer layers of a group at one end of the interchangercrossing over intermediate the ends of the interchanger to form theopposite extreme layers of the group at the other end of theinterchanger to provide conduits of substantially the same length insaid sets, and the respective numbers of conduits in each group beingrelated to each other and to the respective diameters of the groups ofconduits to provide conduits of substantially the same length in saidgroups.

WILLIAM F. GIAUQUE.

REFERENCES CITED The following references are of record in the iile ofthis patent:

UNITED STATES PATmTS Number Name Date 104,326 Long June 14, 1870 429,421Colt June 3, 1890 1,029,981 Fahrman et al. June 18, 1912 1,464,705Goosmann Aug. 14, 1923 1,526,320 Cook Feb. 17, 1925 1,961,202 De BauireJune 5, 1934 2,081,043 Kuhni May 18, 1937 2,141,899 Bennett Dec. 27,1938 2,160,898 Pefl' June 6, 1939 2,241,186 Coons May 8, 1941 FOREIGNPATENTS Number Country Date 912,423 France Fab. 1, 193'!

